Weird - it seems that it "always" supported JPEG. I was always under the impression that GD only supported GIF, GIF+PNG, PNG and then GIF+PNG again, when the GIF patent expired (disregarding fringe formats such as XBM). From browsing through the versions of Makefile.PL, it seems that JPEG support came (unnoticed) in 1.26 , which is the first to check for -ljpeg.

So I must have formed my image of GD in 2000, which is about when I started with Perl, and never updated my assumptions...